One fateful morning, Naho Takamiya is startled to receive a letter supposedly penned by her future self a decade ahead. This mysterious correspondence foretells events scheduled for the same day, initially dismissed as a mere jest by Naho. However, as the letter accurately predicts the arrival of a transfer student named Kakeru Naruse, skepticism gives way to a realization of its authenticity. Through the letter, Naho's older self discloses poignant regrets intertwined with Kakeru, compelling Naho to navigate a path to rectify past missteps. With the weight of foreseen separation from Kakeru looming over her, Naho faces the daunting task of reshaping destinies through the choices she makes.